[PATCH v2] x86/amd/node: Release reserved config regions on init error

[yolezz]

In amd_smn_init(), if pci_request_config_region_exclusive() fails or
if kzalloc_objs() fails to allocate memory for amd_roots, the already
reserved PCI config regions are left allocated.

Use a __free() cleanup helper to automatically release all reserved PCI
config space regions on error exit paths.

Fixes: 83518453074d ("x86/amd_node: Add SMN offsets to exclusive region access")
Signed-off-by: yolezz <yolezz.secret@xxxxxxxxx>
---
v2:
 - Use a __free() cleanup helper instead of manual error rollback, as suggested by Mario.

 arch/x86/kernel/amd_node.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 6a96d888b5a7..20451f0ad8c7 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -239,15 +239,22 @@ static struct pci_dev *get_next_root(struct pci_dev *root)
 	return root;
 }
 
-static void amd_smn_release_config_regions(u16 num_roots)
+static void amd_smn_release_config_regions(u16 *num_roots)
 {
 	struct pci_dev *root __free(pci_dev_put) = NULL;
 
-	/* Release the PCI config space for each root device. */
-	while (num_roots-- && (root = get_next_root(root)))
+	if (!num_roots)
+		return;
+
+	while (*num_roots && (root = get_next_root(root))) {
 		pci_release_config_region(root, 0, PCI_CFG_SPACE_SIZE);
+		(*num_roots)--;
+	}
 }
 
+DEFINE_FREE(amd_smn_release_config_regions, u16 *,
+	    amd_smn_release_config_regions(_T));
+
 static bool enable_dfs;
 
 static int __init amd_smn_enable_dfs(char *str)
@@ -259,9 +266,11 @@ __setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
 
 static int __init amd_smn_init(void)
 {
-	u16 count, num_roots, roots_per_node, node, num_nodes;
+	u16 count, num_roots = 0, roots_per_node, node, num_nodes;
 	struct pci_dev *root __free(pci_dev_put) = NULL;
 
+	u16 *config_regions __free(amd_smn_release_config_regions) = NULL;
+
 	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
 		return 0;
 
@@ -270,7 +279,8 @@ static int __init amd_smn_init(void)
 	if (amd_roots)
 		return 0;
 
-	num_roots = 0;
+	config_regions = &num_roots;
+
 	while ((root = get_next_root(root))) {
 		pci_dbg(root, "Reserving PCI config space\n");
 
@@ -282,7 +292,6 @@ static int __init amd_smn_init(void)
 		 */
 		if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) {
 			pci_err(root, "Failed to reserve config space\n");
-			amd_smn_release_config_regions(num_roots);
 			return -EEXIST;
 		}
 
@@ -297,7 +306,6 @@ static int __init amd_smn_init(void)
 	num_nodes = amd_num_nodes();
 	amd_roots = kzalloc_objs(*amd_roots, num_nodes);
 	if (!amd_roots) {
-		amd_smn_release_config_regions(num_roots);
 		return -ENOMEM;
 	}
 
@@ -327,6 +335,7 @@ static int __init amd_smn_init(void)
 		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
 	}
 
+	config_regions = NULL;
 	return 0;
 }
 
-- 
2.53.0